Cleanup Activities

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Background

The eight-acre Helena Chemical Company (Tampa) Site is located in the Orient Park section of Tampa, Florida. A pesticide manufacturing facility operated on site from 1929 to 1981. Pesticide packaging and distribution activities have continued from 1929 to the present, including during site cleanup activities. EPA placed the site on the Superfund program’s National Priorities List (NPL) in 1992 because of contaminated soil and groundwater resulting from facility operations.

EPA, the Florida Department of Environmental Protection (FDEP) and the site’s potentially responsible party (PRP) have investigated site conditions and taken steps to clean up the site, in order to protect people and the environment from contamination. Site contamination does not threaten people living and working near the site. Both residents and businesses use the public water system for drinking water. By cleaning up soils, identifying an effective groundwater treatment approach and conducting Five-Year Reviews, EPA, FDEP and the site’s PRPs continue to protect people and the environment from site contamination. The most recent Five Year Review is dated March 2016.

What Has Been Done to Clean Up the Site?

Site PRPs lead site investigation and cleanup activities, with oversight provided by EPA and FDEP.

In 2000, PRPs excavated and shipped pesticide-contaminated soil from a retention pond off site for treatment and disposal. In 2004, PRPs removed, treated and disposed of soil contaminated with sulfur and pesticides followed by additional removal of soil contaminated with sulfur and pesticides in 2005. The cleaned-up soil is now usable for commercial and industrial purposes only.

Groundwater contaminated with volatile organic compounds (VOCs) at the nearby Alaric Area Groundwater Plume Superfund site appears to be mixing with the western area of groundwater contamination at the Helena Chemical Company site. In 2006-2007, PRPs sampled site groundwater that showed contamination remaining above cleanup level goals. However, EPA and FDEP did not change the approach to monitored natural attenuation.

In September 2008, the site PRP proposed a series of pilot-scale studies to evaluate the potential biological breakdown of low-level pesticides and xylene remaining in site groundwater. PRPs began these studies in September 2009 and completed them in the summer of 2012. EPA and FDEP reviewed the results of the pilot-scale study and concluded that, with sulfuric acid generation continuing in the vicinity of the former sulfur pit, biological degradation of the hexachlorocyclohexane (HCH, also known as BHC) is not possible. As a result, the PRPs are currently developing plans for the scalable pilot-scale treatability study, designed to raise the pH of the areas impacted by former sulfur pit.

The site’s second Five-Year Review, completed in May 2011, found that cleanup actions to date protect human health and the environment. In the long term, there is a need for additional groundwater cleanup.

What Is the Current Site Status?

In 1996, EPA issued the cleanup plan for the site. It included demolishing tank storage areas and disposing of the debris; digging up material from a former sulfur pit; and disposing of it off site. The plan also addressed soil contamination through neutralizing soils in place; biologically treating contaminated soils and sediments and placing treated soils back on site; and using institutional and engineering controls such as fencing and deed restrictions. The plan also addressed contaminated groundwater though containment and removal; treating groundwater to meet surface water cleanup goals; and discharging treated groundwater to the Tampa Bypass Canal.

In 2005, EPA updated the cleanup plan to make the groundwater cleanup goal for xylene consistent with federal and state primary drinking water standards. EPA anticipates changing the site’s groundwater cleanup method. The Agency is completing a series of studies to determine the most effective option.

In April 2015, while conducting the neutralization pilot study, unexpected contamination was encountered. The subsurface at this location appeared disturbed: paper bags; a black, gelatinous material; and material that resembled elemental sulfur were encountered, along with a very strong odor. The pesticides and insecticides 4,4'-DDT isomers, aldrin, BHC isomers and toxaphene were detected at maximum concentrations of 6,100, 35, 1.6 and 3,200 mg/kg, respectively. This area was removed in March 2017. A total of 454 tons of contaminated soil were excavated and shipped to the Clean Harbors facility in La Porte, Texas.

PRPs anticipate the pilot-scale study, designed to increase the pH of the groundwater, to be completed in 2018. EPA completed the site’s most recent Five-Year Review in March 2016.

Sampling and Monitoring

In September 2008, site PRPs proposed a series of pilot-scale studies to evaluate the breakdown of low-level pesticides remaining in site ground water. In addition, a source area of xylene remains on site, with a shallow area of xylene-contaminated ground water flowing to the southeast. Pilot studies designed to investigate the breakdown and biological degradation of xylene and BHCs were not successful. It was determined that before the BHCs (which are located in the high sulfate soil/groundwater area) can be remediated, the pH needs to be raised to near neutral, or above. Hence, the current pilot study efforts are designed to raise the pH of the former sulfur pit area.

Enforcement Information

EPA issued an order and negotiated a legal agreement with the site owner to investigate and clean up the site. The owner continues to fund site cleanup, monitoring and oversight activities. All area businesses and the residence north of the site use the public water system for drinking water. In addition, EPA and the Southwest Florida Water Management District have entered into an agreement. According to the agreement, the District regulates the permitting process and the construction of water wells within the area of the site’s ground water contamination, as well as within the areas of ground water contamination at the two neighboring Superfund Sites.